Project Summary/Abstract In primary ciliary dyskinesia (PCD), mutations in proteins that play a role in the proper assembly or function of the cilia result in defective ciliary beating, which leads to greatly reduced or absent mucociliary clearance (MCC). The lack of effective MCC results in chronic lung infections, bronchiectasis, chronic sinusitis, and otitis media. Although all PCD subjects have a similar clinical phenotype, the disease is heterogeneous in severity, with some patients having mild symptoms, while others develop severe bronchiectasis. Because mutations in many of the genes that cause PCD have been shown to result in essentially immotile cilia and are expected to result in no MCC, it is not obvious why there exists such a wide range of clinical phenotypes. Our hypothesis is that much of the heterogeneity of disease severity observed in PCD patients is a result of genetic heterogeneity, and that mutations in different genes result in varying levels of residual MCC and consequently, varying severity of disease. Further, we hypothesize that different mutations in the same gene can also result in different levels of ciliary impairment, MCC, and disease severity. Finally, we propose that understanding the mechanistic basis for the differences in disease phenotype will provide targets and opportunities to develop new, personalized treatments for this rare disease. The specific aims are: 1. To investigate the expression and function of genes and proteins, including CFAP57 and PCDP1, mutations of which have been newly shown to cause PCD. Using patient derived human nasal epithelial (HNE) cells and/or induced pluripotent stem (iPS) cells, we will investigate the effect of the mutations at the level of the protein, ciliary function (waveform and beat frequency), and mucociliary transport (MCT) in vitro. 2. To investigate genotype/phenotype relationships in patient derived iPS cells. We will examine the functional consequences of mutations in different genes (CFAP57, PCDP1, RSPH1, CCDC39, and DNAI1) and of different mutations in the same gene (SPAG1, CCDC114, DNAH5) in iPS cells from PCD patients. 3. To investigate the pathogenesis of disease in a mouse model with a deletion of Ccdc39. We will compare the effects of an inducible deletion of Ccdc39 to an inducible of Dnaic1. 4. To investigate the relationship between genotype, MCC, and clinical phenotype in vivo. MCC will be measured in PCD subjects with RSPH1 mutations and compared to PCD subjects with mutations in other genes (e.g., DNAI1, DNAH5). In addition, MCC will be measured after administration of a beta-agonist to determine if MCC can be stimulated in the RSPH1 subjects.